Electrolyte for lithium secondary battery and lithium secondary battery comprising same

Abstract

An electrolyte for a lithium secondary battery which has a non-aqueous organic solvent including a γ-butyrolactone and optionally a cyclic carbonate, an ester compound having an electron withdrawing group, and at least two salts. The lithium secondary battery including the electrolyte has good safety and good storage characteristics at high temperature.

Description

CLAIM OF PRIORITY[0001]This application claims all benefits accruing under 35 U.S.C. §119 from Japanese patent application No. 2003-274875 filed in the Japanese Patent Office on Jul. 15, 2003 and Korean patent application No. 2003-86809 filed in the Korean Intellectual Property Office on Dec. 2, 2003, the disclosures of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. (a) Field of the Invention[0003]The present invention relates to a non-aqueous electrolyte for a lithium secondary battery and a lithium secondary battery comprising the same, and particularly to a non-aqueous electrolyte for a lithium secondary battery having good safety and good storage characteristics at a high temperature, and a lithium secondary battery comprising the same.[0004]2. (b) Description of the Related Art[0005]As lithium secondary batteries comprising non-aqueous electrolytes are known to generate a high voltage, and have a high energy density and good storage characteristi...

AI Technical Summary

Benefits of technology

[0011]It is also an aspect of the present invention to provide a non-aqueous electrolyte for a lithium secondary battery that is capable of ensuring safety and preventing gas generation during storage at a high temperature.

Problems solved by technology

Since most conventional solvents have a low flash point and high inflammability, they may cause dangers such as fire, explosions, and so on.

However, a lithium secondary battery in which a non-aqueous electrolyte is mixed with a halogenated carbonate causes problems in that a film formed on the surface of the negative electrode decomposes to generate a gas, which remarkably increases the internal pressure thereof when the battery is stored around 60° C. for several days.

Particularly, in a case of a polymer battery or a laminated thin lithium secondary battery, it is a serious problem that the battery thickness increases due to the decomposition gas.

In addition, in the case of a polymer battery or a laminated thin lithium secondary battery, internal shorts are repeatedly caused by excessive expansion of the battery volume due to an overcharge.

Particularly, when the battery is overcharged by a large current from a discharged state, it is hard to ensure safety since the internal shorts easily occur due to the lithium deposition.

Images